System and method for dough extrusion

ABSTRACT

A system and method for extrusion of dough is disclosed. The system includes an auger for moving the dough; a metering pump comprising an input; a first motor for actuating the auger to transfer dough to the input of the metering pump; a first encoder for reading a position or speed of the first motor and for transmitting a signal associated with the position or speed of the first motor; and a controller configured to receive the signal from the first encoder to control operation of the first motor. The controller operates the first motor to at least partially counteract a variance in a pressure of dough at the metering pump based signals from the encoder and/or the pressure sensor.

CROSS REFERENCE TO RELATED APPLICATION

The present application is a Divisional of U.S. patent application Ser.No. 12/544,863 titled “SYSTEM AND METHOD FOR DOUGH EXTRUSION” filed Aug.20, 2009, which claims priority from U.S. Provisional Patent ApplicationNo. 61/091,154 titled “SYSTEM AND METHOD FOR DOUGH EXTRUSION” filed Aug.22, 2008, the full disclosures of which are hereby incorporated hereinby reference.

BACKGROUND

The present disclosure relates generally to the field of doughextrusion. More specifically, the disclosure relates to compensation forpressure variance during dough extrusion.

Dough (e.g., for bread, buns, or other flour based dough products) canbe conventionally divided into smaller pieces (e.g., 16-32 ounces) atspeeds ranging from 0 to 200 plus pieces per minute by machine commonlycalled a Rotary Extrusion Divider or, Advanced Dough Divider, forexample as manufactured by AMF, Inc. of Richmond, Va. The RotaryExtrusion Divider conventionally includes an auger (e.g., two screws)contained in a horizontal chamber for kneading and moving the dough to ametering pump, or pumps sometimes via a distribution manifold that canat least partially control the speed of the dough as it is sent to aknife or multiple knifes for cutting at a predetermined size or weight.Other conventional methods of dividing dough may not generally be asaccurate and repeatable as a Rotary Extrusion Divider. Despite theRotary Extrusion Divider being prominent for dividing dough, there hasbeen only been small improvements to the original design of auger screwsfeeding a pump, or pumps.

Due to the rotational nature of the augers, and the operation of themetering pump, the pressure of the dough entering the metering pumpvaries. This pressure variation oscillates generally along a repeatingwave pattern, which reduces the overall accuracy of the Rotary ExtrusionDivider scaling weights and requires that excess or additional dough beincluded with each dough division according to statistical models of theaccuracy and precision of the system performance. Further, this pressurevariation is enhanced by the fixed period of the knife relative to theperiod of the repeating wave pattern.

In recent years, secondary companies have developed add-on machinery tocompliment the Rotary Extrusion Divider. The add-on machinery has helpedto reduce some of the inherent machine scaling deficiencies. Forexample, a machine called a Dough Saver manufactured by Bakery Systems,Inc. of Saint Louis, Mo. is essentially a weight checker typicallypositioned between the Rotary Extrusion Divider and a dough ball conicalrounder, or horizontal rounding bars (however, in some cases because ofspace limitations it is located after the rounder, or bars). The DoughSaver is designed to weigh every dough ball from the Rotary ExtrusionDivider, however in some cases 100% weight measurement is not possible.The computer that controls the Dough Saver and its internal algorithmstypically provides modulating control to the metering pump(s) based onthe dough ball weight measurements. Depending on a predefined set ofweight samples taken, the computer will change the pump speed to varythe weight. However, even with the use of a Dough Saver variability ofweights still exists.

SUMMARY

One embodiment of the disclosure relates to a system for extrusion ofdough. The system comprises an auger for moving the dough; a meteringpump comprising an input; a first motor for actuating the auger totransfer dough to the input of the metering pump; a first encoder forreading a position or speed of the first motor and for transmitting asignal associated with the position or speed of the first motor; and acontroller configured to receive the signal from the first encoder tocontrol operation of the first motor. The controller operates the firstmotor to at least partially counteract a variance in a pressure of doughat the metering pump.

Another embodiment of the disclosure relates to a method for controllingextrusion of dough. The method comprises actuating an auger with amotor; transferring dough to an input of a metering pump using theauger; and operating the motor using the controller to at leastpartially counteract a variance in a pressure of dough at the meteringpump. The method may include reading a position or speed of the firstmotor using an encoder, and transmitting a signal associated with theposition or speed of the first motor from the encoder to a controller.The method may further comprise operating the motor based on the signalassociated with the variance in pressure and based on the signal fromthe encoder.

Another embodiment of the disclosure relates to a system for extrusionof dough. The system comprises an auger; a metering pump comprising aninput; a first motor for actuating the auger to transfer dough to theinput of the metering pump; a controller configured to control operationof the first motor; and a pressure sensor configured to detect apressure of the dough and configured to transmit a signal associatedwith the pressure to the controller. The controller operates the motorto at least partially compensate for a variance in the pressure ofdough.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of a dough extrusion system according to anexemplary embodiment.

FIG. 2 is a schematic view of a dough extrusion system according toanother exemplary embodiment.

FIG. 3 is a schematic view of a dough extrusion system according tostill another exemplary embodiment.

FIG. 4 is a schematic view of a dough extrusion system according to afurther exemplary embodiment.

FIG. 5 is a flow diagram of a dough extrusion method according to anexemplary embodiment.

FIG. 6 is a flow diagram of a dough extrusion method according toanother exemplary embodiment

FIG. 7 is a flow diagram of a pressure variance compensation methodaccording to an exemplary embodiment.

FIG. 8 is an exemplary illustration of a potential improvement byimplementing encoders and pressure variance compensation.

FIG. 9 is an exemplary illustration of another potential improvement byimplementing encoders and pressure variance compensation.

DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

Referring to FIG. 1, a dough extrusion system 10 is configured to dividedough (e.g., viscous materials for making bread, buns, biscuits, rolls,dumplings, pastry, cookies, or other dough-based products) into discretesizes or weights, for example for later packaging, for baking, etc.,according to an exemplary embodiment. Dough extrusion system 10generally includes a hopper 12 that receives dough either in a batch ofvarying sizes, or metered into the hopper 12 via a conveyor, or pipe andguides it to an auger 14. Auger 14 is actuated by a first motor 16,which is driven by a first variable frequency drive (“VFD”) 18, and agearbox 20 via a chain or belt 22. According to various exemplaryembodiments, first motor 16 may be any type of motor capable ofactuating auger 14, for example an asynchronous 3-phase AC motor. Auger14 may include one or more screws that rotate to pass dough to an inputof a metering pump(s) 24. The screws may be open screws or closed screwsaccording to various exemplary embodiments. According to some exemplaryembodiments, the screws may have varied pitches, for example a pitchbetween about 6 and 10 degrees. Due to the rotational nature of augers14, and the operation of the metering pump, the pressure of the doughentering the metering pump 24 varies. This pressure variation oscillatesgenerally along a repeating wave pattern, for example a generallysinusoidal wave or other repeating wave pattern (e.g., see FIG. 8). Forexample, the dough pressure may vary along a repeating wave patternbetween about 20 and 90 pounds per square inch (“PSI”) (per revolution),between about 30 and 80 PSI, between about 40 and 70 PSI, between about50 and 60 PSI, between about 53 and 57 PSI, up to about 65%, up to about45%, up to about 27%, up to about 10%, up to about 3.5%, or othervariation along a repeating wave pattern.

Metering pump(s) 24 is actuated by a second motor(s) 26 driven by asecond variable frequency drive(s) 28. According to various exemplaryembodiments, metering pump(s) 24 may be a positive displacement pump orany other type of pump capable of receiving dough and outputting thedough at a generally constant rate with minimal variation. Metering pump24 outputs the dough at a generally constant speed through a pipe andshape to a cutting device or knife(s) 30 (e.g., cutting or slicingdevice, etc.) that cuts the dough into discrete sizes. Knife 30 isactuated by a third motor(s) 32 driven by a third variable frequencydrive(s) 34 and may be any knife capable of cutting dough. A conveyor orother material handling system or apparatus may be located at the outputof knife 30.

It is noted that while a single metering pump 24, second motor 26,second variable frequency drive 28, knife 30, third motor 32, and thirdvariable frequency drive 34 are illustrated, according to otherexemplary embodiments, system 10 may include more than one of each thesecomponents. For example, system 10 may include a manifold coupled toauger 14 for dividing the dough into multiple lines for cutting. Each ofthe multiple lines may include a respective metering pump, second motor,second variable frequency drive, knife, third motor, and third variablefrequency drive 34. In other embodiments, the manifold may be locatedbetween the metering pump and the knife, or at the output of the knife.

As the dough passes from auger 14 to metering pump(s) 24, a pressuretransducer or sensor 36 measures the pressure of the dough at the inputof metering pump 24. An electrical signal representing the pressurereading is sent to a proportional-integral-derivative (“PID”) loopcontroller 38 coupled to first variable frequency drive 18. PID loop 38and first variable frequency drive 18 then output a signal to firstmotor or auger motor 16 to adjust the speed of auger 14 to provide anamount or pressure of dough to metering pump 24 with little variance.According to various exemplary embodiments, pressure sensor 36 can beany type of absolute or relative pressure sensor capable of sensing thepressure of the dough at metering pump 24. According to alternativeexemplary embodiments, pressure sensor 36 may be replaced by any of avariety of technologies capable of measuring or detecting volume,weight, mass, density, or other characteristic of dough.

PID control loop 38 may receive an input variable in the process beingmeasured (a process variable (“PV”)) and compare it to a processsetpoint (SP) to eliminate or reduce an error or difference between theprocess variable and setpoint. The error can be caused by naturaltendencies in system 10 or by an external disturbance. PID loop 38calculates a control variable (CV) that is output to a system devicethat has influence over the process variable. In the illustratedexemplary embodiments, the setpoint is the desired pressure, the processvariable is the actual pressure read from pressure sensor 36, and thecontrol variable is a speed command to auger motor 16 that has a directeffect on the pressure. PID loop 38 may provide a generally constantpressure at the desired setpoint to allow consistent metering bymetering pump 24, resulting in more accurate and consistent dough pieceweights.

The PID loop mathematics operate on control systems feedback loop theoryusing three parameters. The “P” in the system is the proportional termused to designate the proportional response of the error between processvariable and setpoint. The higher the proportional gain, the larger theresponse to error. The “I” in the system is the integral term andgenerally provides a proportional response by analyzing past errorvalues over time. The integral term can reduce error faster thanproportional control alone but also can cause the process variable toovershoot after reaching setpoint since it is using past values. The “D”is the derivative term of loop control and provides a response to theerror by looking at the rate of change of the error to predict futureerror values and eliminate them. The derivative term may counteract theintegral overshooting but slow down the response as well. The threeparameters are generally tuned to values that are appropriate for aparticular system, for example dough extrusion system 10. According tovarious exemplary embodiments, any one of several tuning methods andtheories may be used that take into account different parts and types ofthe dough extrusion process.

Each of first variable frequency drive 18, second variable frequencydrive 28, and third variable frequency drive 34 may also be coupled to amanual potentiometer 39 configured to allow an operator to manuallyadjust the speed of first motor 16, second motor 26, and third motor 32.According to some exemplary embodiments, a vacuum pump 40 may be placedin the auger chamber. Vacuum pump 40 is generally configured to “degas”the dough or remove air pockets in the dough and assist in the movementof dough in hopper 12 into the auger (14). Vacuum pump 40 may be anyvacuum pump of past, present, or future design that is capable ofremoving air. It is noted that according to other exemplary embodiments,vacuum pump 40 may be omitted.

Referring to FIG. 2, a dough extrusion system 100 similar to system 10of FIG. 1 is configured to divide dough into discrete sizes or weights,for example for later packaging, for baking, etc., according to anexemplary embodiment. System 100 includes a programmable logiccontroller (“PLC”) 102 instead of PID controller 38 or including the PIDlogic. PLC 102 can adjust first, second, and/or third variable frequencydrives 18, 28, and/or 34 to control the speed of first motor 16/auger14, second motor(s) 26/metering pump(s) 24, and/or third motor(s)32/knife(s) 30 based on pressure readings from pressure sensor 36.According to various exemplary embodiments, PLC 102 can be any PLC ofpast, present, or future design that is capable of controlling thevariable frequency drives or the speed of the motors in extrusion system100.

PLC 102 may be coupled to a user or operator interface 104 to allow anoperator to monitor and adjust the machine more easily. Interface 104may include a recipe management system to facilitate the storage ofoperating variables (e.g., in a memory) depending on the type or recipeof dough, including individual PID loops, parameters and allow a morerapid “one step” changeover.

Actuation of the auger screws may cause a natural variation in pressureat metering pump 24. For example, the shape and rotation of the screwsmay cause a naturally occurring repeating wave pattern effect, reducingthe effectiveness of PID loop control and causing variation in the doughpressure at metering pump 24 and reducing the overall accuracy of theRotary Extrusion Divider scaling weights.

Referring to FIG. 3, a dough extrusion system 200 is configured todivide dough into discrete sizes or weights, for example for laterpackaging, for baking, etc., according to another exemplary embodiment.Auger 14, metering pump(s) 24, and pressure sensor 36 at the input ofmetering pump 24 may be generally similar to those like parts of FIGS. 1and 2.

According to the illustrated exemplary embodiment, a first motor 202 andgearbox 204 (the auger drive motor assembly) may be a servo motor, ACpermanent magnet motor, or AC synchronous motor that uses feedback froma first encoder 206 and a zero or close to zero backlash gearbox,respectively. Servo and servo control technology may allow cam profilingto be set up in conjunction with PID control. A controller 208 (e.g., aPLC controller) can use a cam profile to take the shape and rotation ofthe auger screws into account and counteract the natural cam effect toreduce or eliminate the varying dough pressure. A different cam profilecan be setup for each type of dough, if necessary. Gearbox 204 isconfigured to allow less backlash of the gears and to have highertolerance for speed change. Gearbox 204 may have a speed ratio of about50:1, to 25:1, or any other suitable ratio which can be achieved via thegearbox, or pulley ratios from the gearbox to the auger drive. The servomotor and servo control may allow for more precise speed and positioncontrol and may permit use of maximum torque throughout the speed range.Alternatively, first motor 202 may be a vector motor with encoder 206feedback. A second motor 210 and a third motor 212 for metering pump(s)24 and knife(s) 30 may be vector or servo motors that use feedback froma second encoder 214 and a third encoder 216, respectively. One or moreof the motors can also be AC motors with a turn down ratio of 1000:1 orgreater.

Use of vector or servo motors for auger, metering pump, and/or knifemotors 202, 210, and/or 212 may increase the speed resolution accuracyof system 200. For example, the resolution or speed control accuracy mayincrease from a range of 0.5%-2% to a range down to 0.001%. The encoderscoupled to each motor may be configured to provide a signal to avariable frequency drive and/or PLC 208 that represents an absoluteposition, an absolute speed, and/or notification of a slip of therespective motor. If PLC 208 receives a signal representative of themotor position, it may calculate the speed based on a history ofpositions at various times. In the illustrated exemplary embodiments,encoders 214 and 216 coupled to second motor 210 and motor 212,respectively, are configured to provide data to variable frequency drive28 or 34 controlling the respective motor. Encoder 206 coupled to firstmotor 202 is configured to provide data to first variable frequencydrive 18 and PLC 208 via a signal splitter 218 that sends the data toboth variable frequency drive 18 and PLC 208. According to alternativeexemplary embodiments, encoders 206, 214, and/or 216 may be omitted andmotors 202, 210, and/or 212 can be vector motors that provide vectorfeedback to the respective variable frequency drive or PLC 208.

Auger 14 may also be coupled to a “home” reference or cam proximityswitch 219 configured to reset the position of auger 14 screws to anoriginal home or reference position. PLC 208 may communicate with switch219 to control when auger 14 is reset. By resetting auger 14 to thereference position, PLC 208 knows the position of auger 14 and, withvariable frequency drive 18, can more accurately adjust motor 202 andthe speed and position of auger 14.

It is noted that while a single metering pump 24, second motor 210,second variable frequency drive 28, third motor 212, third variablefrequency drive 34, second encoder 214, third encoder 216, and knife 30are illustrated, according to other exemplary embodiments, system 200may include more than one of each these components. For example, system200 may include a manifold coupled to auger 14 for dividing the doughinto multiple lines for cutting. Each of the multiple lines may includea respective metering pump 24, second motor 210, second variablefrequency drive 28, third motor 212, third variable frequency drive 34,second encoder 214, third encoder 216, and knife 30.

The motors may operate in a given frequency band, for example up toabout 70 Hz, between about 60 and 70 Hz, between about 63.5 and 63.9 Hz,at a frequency modulating up to about 1.5 Hz, etc. For a range betweenabout 63.5 and 63.9 Hz with a modulation of 0.4 Hz, a conventionalresolution of 1% leaves an error of up to about 0.64 Hz, which isgreater than the typical modulation of the motor. By increasing theresolution to 0.001%, in the same example, the error may be only 0.00064Hz, which is well within the operating range of the motor.

The encoder data sent to PLC 208 may be used in conjunction with thepressure data from pressure sensor 36 to determine the speed that eachmotor should be run at a given point in time. PLC 208 is configured tosend control signals (e.g., digital, analog, etc.) to variable frequencydrives 18, 28, and 34 via a switch 220. Switch 220 is configured toroute PLC 208 signals to the appropriate one or more variable frequencydrives to drive the motors and deliver a generally constant doughpressure for cutting. According to some exemplary embodiments, switch220 may be an Ethernet switch and the control signals may be sent tovariable frequency drives 18, 28, and 34 with an Ethernet communicationprotocol. According to another exemplary embodiment, the control signalmay be a direct analog control signal that is readable by PLC 208.According to other exemplary embodiments, the communication protocolbetween PLC 208 and the variable frequency drives may be another serial,parallel, USB, Firewire, WiFi, WiMAX, Bluetooth, RF, Control Net, DeviceNet, Remote IO, DH485, CAN, any other wired or wireless protocol, or anyprotocol capable of facilitating communication between PLC 208 andvariable frequency drives 18, 28, and 34. In these exemplaryembodiments, switch 220 may be any appropriate switch capable of routingthe communication signals.

PLC 208 may be coupled to a user or operator interface 222 to allow anoperator to monitor and adjust the machine more easily. Interface 222may include a recipe management system to facilitate the storage ofoperating variables (e.g., in a memory) depending on the type or recipeof dough, including individual PID loops, parameters and allow a morerapid “one step” changeover.

According to some exemplary embodiments, vacuum pump 40 may be placed inthe auger chamber and auger 14. Vacuum pump 40 is generally configuredto “degas” the dough or remove air pockets in the dough and assist indough entering the auger chamber. Vacuum pump 40 may be any vacuum pumpof past, present, or future design that is capable of removing airpockets in dough. It is noted that according to other exemplaryembodiments, vacuum pump 40 may be omitted.

Referring to FIG. 4, a dough extrusion system 300 similar to system 200of FIG. 3 is configured to divide dough into discrete sizes or weights,for example for later packaging, for baking, etc., according to anexemplary embodiment. Dough extrusion system 300 includes a secondpressure sensor 302 at the output of each metering pump 24 to providePLC 208 with a second pressure reading. The second pressure reading mayallow for greater control over dough extrusion system and may allow forisolation as to where any variance is occurring. For example, PLC 208may be able to determine whether a variance is primarily due to theactuation of auger 14 or due to actuation of metering pump 24.

Referring to FIG. 5, a method 500 for counteracting variance in doughpressure or weight in a dough extrusion system (e.g., dough extrusionsystem 10, 100, 200, and/or 300) is shown, according to an exemplaryembodiment. Auger 14 of the dough extrusion system is actuated by motor16 or 202 (step 502), transferring dough to metering pump 24 (step 504).Motor 16 or 202 for actuating the auger is operated to counteractvariance in dough pressure at metering pump 24 (e.g., before and/orafter metering pump 24) (step 506). According to various exemplaryembodiments, the operation of motor 16 or 202 may be adjusted at variousintervals, for example at about 1 second intervals, at about 10 secondintervals, at about 100 millisecond intervals, at about 10 millisecondintervals, etc.

Referring to FIG. 6, a method 600 for counteracting variance in doughpressure in a dough extrusion system (e.g., dough extrusion system 10,100, 200, and/or 300) is shown, according to another exemplaryembodiment. Dough is fed to auger 14 (e.g., from hopper 12) (step 602)and actuation of auger 14 (step 604) transfers the dough to meteringpump 24 (step 606). The system measures the pressure of the dough at theinput and/or output of metering pump 24 at a predetermined interval(step 608). The speed of one or more motors in the system is measured(step 610), for example by encoders or by vector feedback at the same ora different predetermined interval as the dough pressure measurement. Acontroller (e.g., PLC 208, PID loop 38, etc.) determines an appropriatespeed or adjustment to the speed for each of the one or more motors thatmay at least partially counteract a measured variance in dough pressure(step 612), for example motors 16, 26, and 32 or motors 202, 210, and212. The system then operates the one or more motors to be adjusted(e.g., via variable frequency drives) to counteract the variance indough pressure (step 614). It is noted that the actuation of auger 14and/or metering pump 24 may be independent of the measuring of doughpressure and motor speed.

The above described dough extrusion systems are configured to reduce thevariance in dough pressure moving through the system, thereby reducingthe amount of excess or additional dough included with each doughdivision according to statistical models of the accuracy and precisionof the system performance. Specifically, the systems may compensate(i.e., counteract, offset, neutralize, balance, make up for, etc.) for avariance in dough pressure (e.g., repeating wave pattern) caused by therotation of the auger 14. For example, the PLC or PID loop may detectthe pressure variance via the first sensor and/or the second sensor. ThePLC or PID loop may then adjust one or more of the motors accordingly tocompensate for or counteract the pressure variance, for example byreading the speed and/or position of the motor by reading an encoder andadjusting the phase of the motor to counteract the phase of the auger.Because the pressure variance may not perfectly match a mathematicalrepeating wave pattern (e.g., a sinusoidal wave), the PLC or PID loopmay use the pressure and encoder readings to adjust the motors tocompensate for or counteract the variance. Alternatively, in someexemplary embodiments, the variance may be very similar to amathematical repeating wave pattern (e.g., a sinusoidal wave) and PLC orPID loop may automatically execute operations or a program to cause themotors to compensate for or counteract an expected mathematical pattern.

Control of dough metering pump 24 input pressure for divider system 300and 400 may be accomplished by precise and constant dough material flowfrom dough auger 14 to metering pump 24. By its nature, an auger has arepeating wave pattern material flow effect and may even include aportion where reduced or no material flow occurs.

The pressure variance compensation function described above may use avariety of control profile technologies to offset the mechanical auger14 repeating wave pattern material flow pattern. The pressure variancecompensation hardware may include the use of programmable logiccontroller 208 (e.g., such as commercially available from AB ControlLogix), a closed loop controller (e.g., a servo controller residing inPLC 208), an AC variable frequency drive (e.g., variable frequency drive18, 28, and/or 34), and an AC asynchronous motor (e.g., motor 202, 210,212, and/or a servo motor), for example having an encoder (e.g.,encoders 206, 214, 216, and/or a 1024 pulse per revolution quadratureencoder) and reduction gearbox (e.g., gearbox 204). According to someexemplary embodiments, the control profile technology used may beconfigured to electronically represent a mechanical cam or othermodulation effect.

An additional PID (Proportional, Integral, and Derivative) control looplocated in PLC 208 may be used to adjust the speed of the controlprofile to maintain the output of auger 14 at a generally constantpressure set point. This PID loop uses auger pressure sensor 36 locatedat the input of metering pump 24 as the process variable and the controlprofile speed as the control variable.

Referring to FIG. 7, the control functions are sequenced in programmablecontroller 208 using a method 700. First, PLC 208 sets/initiates thepressure set point for the PID, which then defines the speed of auger 14(step 702). Second, the portion of auger 14 where reduced or no materialflow occurs is located and controlled. This is accomplished by actuatingreference proximity switch 219 located on the drive pulley of auger 14(step 704). Once the pressure variance compensation function is engaged,proximity switch 219 may locate the “home” or reference positiondynamically while auger 14 is moving and may provide the referenceposition to the closed loop position controller in PLC 208. Third, oncethe reference position is located, PLC 208 engages the pressure variancecompensation function automatically and engages a predefined electronicposition control profile synchronized to the reference position (step706). This pressure variance compensation function repeats with everyrevolution of auger 14 and drives the speed of the motor in a repeatingwave pattern profile (e.g., speed/velocity, etc.) to offset themechanical effect of auger 14. The predefined control profile (e.g., tocompensate for a generally sinusoidal or other repeating wave pattern)may be updated based on measurements taken by pressure sensor 36 and/orpressure sensor 302.

By this method, the repeating wave pattern material flow effect may beoffset by the position controller in PLC 208 and the pressure set pointmay be attained by use of the PID resulting in reduced variation ofmetering pump 24 input pressure and less variation in the material flowto metering pump 24.

FIG. 8 is an exemplary illustration of a potential improvement in doughpressure by implementing encoders and pressure variance compensation.The graph illustrates a potential comparison of dough pressures betweena system using pressure variance compensation (e.g., system 200, system300, etc.) and a system not using encoders or pressure variancecompensation, according to one exemplary embodiment. The system notusing encoders or pressure variance compensation includes a doughpressure (e.g., as measured by sensor 36) having a repeating wavepattern over a number of sample points or for each revolution of thescrews of auger 14. For example, the dough pressure may vary along arepeating wave pattern between about 20 and 90 PSI (per revolution),between about 30 and 80 PSI, between about 40 and 70 PSI, between about50 and 60 PSI, between about 53 and 57 PSI, up to about 65%, up to about45%, up to about 27%, up to about 10%, up to about 3.5%, or otherrepeating wave pattern variation.

The system using encoders or pressure variance compensation generallyhas less variation in dough pressure (e.g., as measured by sensor 36).For example, the dough pressure may have a variance of up to about 2%,up to about 1.5%, up to about 1%, less than 1%, etc. It is noted thatalthough specific pressures and pressure variances have beenillustrated, according to other exemplary embodiments, lower or higherpressures or pressure variances may be realized depending on the type ofdough and the specific system configuration, however the variance isgenerally decreased in the system compensating for or counteracting therepeating wave pattern effects.

FIG. 9 is an exemplary illustration of a potential improvement in doughweight distribution by implementing encoders and/or pressure variancecompensation. The graph illustrates a potential distribution of doughweights for a system using encoders and pressure variance compensation(e.g., system 200, system 300, etc.) and a system not using encoders orpressure variance compensation, according to one exemplary embodiment.The system not using encoders or pressure variance compensation includesa dough pressure (e.g., as measured by sensor 36) having a repeatingwave pattern over a number of sample points or revolutions of the screwsof auger 14, as described above. This variation in dough pressure causesa greater variation or distribution of dough weights after being cut byknife 30. Because the system using encoders and pressure variancecompensation generally has less variation in dough pressure, it may alsoallow for less distributed weights of dough pieces closer to a minimumcut-off weight (“minimum label weight”) that is required to meet theweight provided on the product packaging. For example, the savingsprovided by the encoders and the pressure variance compensation can beestimated by (μ2−μ1).

As illustrated, the system not using encoders or compensating forrepeating wave pattern effects has a mean dough weight that is higherthan the mean dough weight in a system that does compensate for therepeating wave pattern effects. Further, the system not compensating forrepeating wave pattern effects has 1^(st), 2^(nd), and 3^(rd) sigma orstandard deviation values that are higher than those of the system thatdoes compensate. By compensating for or counteracting repeating wavepattern effects, a lower weight of dough may be cut-off by knife 30while still meeting the minimum cut-off weight requirements/goals.Because less dough is used, the cost of producing the product may bereduced with the decreased weight, for example the cost may be reducedby the difference between (μ2−μ1) such as in the example of FIG. 9.

It is important to note that the terms “motor,” “variable frequencydrive,” “auger,” “knife,” and “metering pump” are intended to be broadterms and not terms of limitation. These components may be used with anyof a variety of dough products or arrangements and are not intended tobe limited to use with dough applications. For purposes of thisdisclosure, the term “coupled” shall mean the joining of two membersdirectly or indirectly to one another. Such joining may be stationary innature or movable in nature. Such joining may be achieved with the twomembers or the two members and any additional intermediate members beingintegrally formed as a single unitary body with one another or with thetwo members or the two members and any additional intermediate memberbeing attached to one another. Such joining may be permanent in natureor alternatively may be removable or releasable in nature. Such joiningmay also relate to mechanical, fluid, or electrical relationship betweenthe two components.

It is also important to note that the construction and arrangement ofthe elements of the dough extrusion system as shown in the preferred andother exemplary embodiments are illustrative only. Although only a fewembodiments of the present invention have been described in detail inthis disclosure, those skilled in the art who review this disclosurewill readily appreciate that many modifications are possible (e.g.,variations in sizes, dimensions, structures, shapes and proportions ofthe various elements, values of parameters, mounting arrangements,materials, colors, orientations, etc.) without materially departing fromthe novel teachings and advantages of the subject matter recited in theclaims. For example, while the components of the disclosed embodimentswill be illustrated as a system and process designed for a doughproduct, the features of the disclosed embodiments have a much widerapplicability—the dough extrusion system design is adaptable for otherdough products that are metered and/or cut. Further, the size of thevarious components and the size of the containers can be widely varied.Accordingly, all such modifications are intended to be included withinthe scope of the present invention. The order or sequence of any processor method steps may be varied or re-sequenced according to alternativeembodiments. Other substitutions, modifications, changes and/oromissions may be made in the design, operating conditions andarrangement of the preferred and other exemplary embodiments withoutdeparting from the spirit of the present invention.

What is claimed is:
 1. A system for extrusion of dough, the systemcomprising: an auger; a metering pump comprising an input; a first motorfor actuating the auger to transfer dough to the input of the meteringpump; a first encoder for reading a position or speed of the first motorand for transmitting a signal associated with the position or speed ofthe first motor; a controller adapted to receive the signal from thefirst encoder to control operation of the first motor; wherein thecontroller operates the first motor to at least partially counteract avariance in a pressure of dough at the metering pump by driving thefirst motor in accordance with a repeating wave pattern profile toadjust the speed of the auger throughout at least every singlerevolution of the auger in accordance with a first set of intervals, thepressure of the dough being detected in accordance with a second set ofintervals.
 2. The system of claim 1, wherein the controller operates thefirst motor to counteract the variance in the pressure of the doughbased on a signal associated with the variance in pressure and based onthe signal received from the first encoder.
 3. The system of claim 1,further comprising: a pressure sensor configured to detect the variancein the pressure of dough at the input of the metering pump and adaptedto transmit a signal associated with the variance in pressure to thecontroller, wherein the controller operates the first motor based on asignal associated with the variance in pressure and based on the signalreceived from the first encoder.
 4. The system of claim 3, wherein thecontroller comprises a closed loop feedback system adapted to processthe signal associated with the variance in pressure to generate a doughextrusion control signal following a predetermined decrease or apredetermined increase in the magnitude of pressure detected by thepressure sensor.
 5. The system of claim 3, further comprising: a secondmotor for actuating the metering pump; a cutting device adapted toreceive dough from the metering pump; a third motor for actuating thecutting device; a second encoder for reading a position or speed of thesecond motor and for transmitting a signal associated with the positionor speed of the second motor; a third encoder for reading a position orspeed of the third motor and for transmitting a signal associated withthe position or speed of the third motor; wherein the controlleroperates the first, second, and third motors based on the signalassociated with the variance in pressure and based on the signalsreceived from the first, second, and third encoders.
 6. The system ofclaim 1, further comprising: a second motor for actuating the meteringpump; a cutting device adapted to receive dough from the metering pump;a third motor for actuating the cutting device; a second encoder forreading a position or speed of the second motor and for transmitting asignal associated with the position or speed of the second motor; athird encoder for reading a position or speed of the third motor and fortransmitting a signal associated with the position or speed of the thirdmotor; wherein the controller operates the first, second, and thirdmotors based on the signals received from the first, second, and thirdencoders.
 7. The system of claim 6, further comprising a switch forrouting signals between each of the first, second, and third motors andthe controller and for routing signals between each of the first,second, and third encoders and the controller.
 8. The system of claim 6,wherein at least one of the first motor, second motor, and third motoris a variable frequency drive motor.
 9. A method for controllingextrusion of dough, the method comprising: actuating an auger with amotor; transferring dough to an input of a metering pump using theauger; operating the motor using a controller to at least partiallycounteract a variance in a pressure of dough at the metering pump inaccordance with a repeating wave pattern profile to adjust speed of theauger throughout at least every single revolution of the auger inaccordance with a first set of intervals, the pressure of the doughbeing detected in accordance with a second set of intervals.
 10. Themethod of claim 9, further comprising sensing the variance in pressureof dough at the input of the metering pump.
 11. The method of claim 10,further comprising transmitting a signal associated with the variance inpressure to the controller.
 12. The method of claim 11, furthercomprising reading a position or speed of the motor using an encoder,and transmitting a signal associated with the position or speed of themotor from the encoder to a controller
 13. The method of claim 12,further comprising operating the motor based on the signal associatedwith the variance in pressure and based on the signal from the encoder.14. The method of claim 11, further comprising using the pressure of thedough as a process variable and the speed of the auger as a controlvariable.
 15. The method of claim 14, further comprising identifying andcontrolling a dead spot of the auger by a reference position of theauger, wherein the dead spot of the auger is an auger position wherelittle or no material is moved by rotation of the auger.
 16. The methodof claim 15, further comprising initiating a position profilesynchronized to the reference position.
 17. The method of claim 16,further comprising repeating a correction function with each revolutionof the auger to provide the augur with the repeating wave patternprofile.